NASA managers on Wednesday confirmed that the earliest scheduled launch date for the space shuttle Discovery has been moved back one week, to May 22.

On Tuesday, NBC News quoted its sources as saying the postponement was expected.

Shuttle program managers met this week to certify the new safety measures and fixes made to Discovery, which will be the first shuttle to fly since Columbia's catastrophic breakup on Feb. 1, 2003.

NASA is running behind on the training schedule for Discovery's crew, as well as on the pre-flight preparations of some redesigned equipment. As a result, shuttle managers decided to move the opening of Discovery's launch window from May 15 to May 22.

"We decided to go ahead and make the launch date the 22nd," shuttle program manager Bill Parsons told reporters Wednesday.

He noted that under the previous schedule, managers would have to conduct their flight readiness review — a key milestone in the preparations for flight — next week.

"It became obvious that we had done a lot of work ... but we also saw that there were still a certain amount of analysis that needed to be done. And we needed to do that prior to the flight readiness review," Parsons said.

Beyond June 3, "you begin to have some uncertainty" about lighting conditions for the imagery required to document the performance of the external fuel tank, deputy shuttle program manager Wayne Hale explained.

Investigators say that Columbia's left wing was damaged by debris that fell off the fuel tank just after launch, setting the stage for catastrophe during the shuttle's atmospheric re-entry 16 days later. As a result, NASA wants to make sure Discovery's launch phase is closely monitored.

Hale said launch managers were still studying the potential for ice to accumulate and break off from three areas on the fuel tank and its fittings. Also, engineers were still stress-testing a camera-equipped boom that the crew would use to inspect the shuttle's exterior in orbit.

Hale and Parsons said they thought all the work could be done in time for a May 22 launch. "I'm very confident that the team has its arms around this, and we know exactly what we want to do to get to the May 22 time frame," Parsons said.

But they also acknowledged that further delays could arise. "We’re going to launch when we’re ready to launch, and not before,” Hale said.

If Discovery cannot be launched during the May-June opportunity, the next chance would come in July, and the shuttle Atlantis' scheduled launch would likely be postponed until September.

Bound for the space station
Discovery's 12-day mission is aimed at bringing much-needed supplies to the international space station, as well as testing tools and techniques for checking the shuttle's protective skin and making repairs if necessary.

Hale said mission managers were working with Discovery's crew on the repair procedures and other aspects of preparation for the flight. "They want to make sure that we're doing a good and thorough job. ... Frankly, we've got a couple more discussions to have with them before we go launch," he said.

A successful flight by Discovery would kick off a five-year flight schedule aimed almost exclusively at completing construction of the space station. By the year 2010, the shuttle fleet is due for retirement, and NASA plans to develop a new type of space vehicle for sending astronauts to the moon by 2020.

The 12 orbiting astronauts on the International Space Station were hailed by the chief on Thursday — and also got a humorous scolding for keeping their android crewmate locked up in its packing for so long.